In what format does WSPR send the data. By this I mean does it:

- send the user data a number of times in each 2min segment? In this case does it send all the data and then repeat it all or does it send some fraction of the data, repeat that and then send another fraction, repeat and so on

- have a start and end code much like SSTV

- pick up a "partial" transmission if it misses the start or the tx clock is say 1 min out of sync?

Also, what is the "weakest" signal that WSPR can decode?

Thanks

Tim R